1. Field of the Invention
The present invention relates to surgical instruments used to perform circular anastomosis of tubular tissue sections and, more particularly, to a surgical instrument suitable for installation of multi-ring compression devices for circular anastomosis of tubular tissue sections.
2. Description of Related Art
Some surgical procedures, such as repair of the colon, require the joining of two rather large sections of tubular tissue. During these procedures, a diseased area of tissue is excised leaving two free ends of healthy tissue to be joined. Some known methods of joining the tissues include stapling or suturing the ends together. A more recent advancement in the art, called a multi-ring compression device, is used to clamp the free ends of the tissue between a series of interlocking rings whose centers are then cut away.
Typically, a multi-ring compression device consists of an outer ring assembly which fits over an intermediary ring. The two rings are then locked together by inserting an inner ring in the intermediary ring which locks in place.
In use the free open ends of tissue are captured between the outer ring assembly and the intermediary ring. The entire assembly is then locked together by insertion of the inner ring. The inner core of the ring assembly is then cut away along with any excess tissue. The clamped tissue within the rings is deprived of blood causing necrosis to take place. The outer tissue heals while the necrosised inner tissues and clamps are detached and expelled by the body. Newer clamps or compression rings, such as those shown in U.S. Pat. No. 4,966,602, have a fragmentable structure which enhances the bodies ability to expel the device.
Various surgical instruments have been developed to install the multi-ring compression devices. One known surgical instrument used to install the compression rings is shown in U.S. Pat. No. 4,681,108 to Rosati et al. This instrument generally comprises a cylindrical housing having means for aligning the rings within the tubular tissue sections, driving means for clamping the rings together in locking arrangement around the tissue sections and cutting means for removing excess tissue ends and detaching the instrument from the rings. In the Rosati et al. instrument, the cutting means consists of an advancing circular blade which both cuts the tissue and rings and pushes the rings free of the instrument in one continuous stroke.
Another known instrument for installing multi-ring compression devices is shown in U.S. Pat. No. 4,907,591 to Vasconcellos et al. This instrument includes such features as a rotating cutting blade and locking means to isolate the operation of aligning and clamping the rings from the separate continuous operation of cutting the excess tissue and freeing the instrument from the tissue.
Still other instruments, such as the flexible bronchoscope shown in U.S. Pat. No. 4,880,015 to Nierman, include provisions for insertion of accessory instruments such as biopsy forceps through the instrument in order to access the operative site. U.S. Pat. No. 4,817,847 to Redtenbacher discloses a circular stapling device having a removable anvil head provided with means to attach an endoscope to the anvil head.